Composition and method of inhibiting corrosion of metal surfaces in contact with aqueous surface active solutions



,cyclie ring compounds with three hetero-atoms com- UniteclStates Patent .l"

N N 3,245,915 N l\ l N COMPOSITION AND METHOD F INHIBITING N M N Ru CORROSION OF METAL SURFACES 1N CON- N I TACT WITH AQUEOUS SURFACE ACTIVE SOLUTIONS g- 32 i: 51; lg fg ggg g fifif i fifi gf gk wherein, in Formulae 1-3, M is a metal, R is a substitupany of balifornia, Los Angeles, Calif., a corporation em group R f .bsmuent group m n has a i of of California 0 to 4; R and R being the same or difierent substituents No Drawing. ,Filed Dec. 17, 1962, Ser. No. 244,921 from the group consisting of alkyl radicals of 1 to 10 car- I v14 Claims. (Cl. 252-137) 10 bon atoms, the group consisting of alltoxy radicals of 1 to 10 carbon atoms, aryl radicals of 6 to 18 carbon tors comprising innermetallic complexes of benzotriazoles, 32 1 gg i g gb g figg z gfifg gfg i g to corrosion-inhibiting compositionscontaining same, and i' 5 m dicalls that is having 1 m 10 carbon l g g; s: 33331:: ggg ffs gggi Sald compounds 10 alkyl portion and 6 to 18 carbon atoms in the aryl portion cycloaliphatic hydrocarbon radicals of 3 to 7 carbon atoms,

one of the first members of thg-i'filve membemd hetero nitro and halogens, and M being copper, nickel or cobalt, in the preferred embodiment of the invention. Com- 20 pounds of the associated type wherein the above penetration type compounds are associated as positive ions with This invention relates to certain novel corrosion inhibiprises} the 1,2,3-triazoles, which exist in three tautomeric forms of which the following isof interest herein:

such negative ions or anions as halides, nitrate, sulfate, g phosphate, etc., are also contemplated.

It becomes, then, a primary object of this invention to f provide corrosion inhibitors comprising compounds corresponding to Formulae 1 to 3.

y Another object of this invention is to provide a method There are a methods of Prepanng. the L234naz01ev of inhibiting corrosion using compounds corresponding to including the action of hydrazoic acid or its organic Formulae 1 to e at the aZideS, 011 acetylfinic F the Still another object of this invention is to provide comdatiOIl of p y 053201165 to Qt i undergo positions for use in inhibiting corrosion wherein said g Contraction in the P WW of hot acld; and the compositions include an effective amount of compounds tion of nitrous acid on o-phenylene diamide to form az1- col-responding to Formulae 1 to mido-benzene, as one form of compound wherein the An object of this invention is to provide a new use hetefocyclic nucleus condensed in the orthoposmon for innermetallic complexes of benzotriazoles and naph- 3,245,915 Ce Patented Apr. 12, 1966 7 with a benz n 11615118! I thotriazoles as corrosion inhibitors for aerated aqueous solutions in contact with a metal surface.

These and other Objects of this invention will be described or become apparent as the specification proceeds. 40 The compounds or complexes to be used in accordance with this invention are prepared by reacting the corresponding benzotriazole or naphthotriazole with an acidic The ring system of the molecule is very stable, even remetal salt in an alcohol solution, followed by the addition sisting powerful oxidation, and only reducing agents will of an alkali. Species of benzotriazoles and naphthotriattack it. Thetriazoles are veryweak bases. The hydroazoles that can be used as starting materials to prepare the gen atom attached to the nitrogen can be replaced by a innermetallic complexes include but are not limited to: metal. Benzo-1,2,3-triazole (a ziminobenzene) melts at 4 meth lbenzotriazole about 100 C., and the methyl derivative, azimino-toluene 4 ethylzenzotriazole melts at 4-isopropylbenzotriazole In accordance with this invention, we have found that d 0 2 100 4 n propylbenzotriazole small amounts, 1n the order of about 0.0001 to g./ 4 n butylbenzotriazole ml, of solution, of innermetallic complexes of benzotri- 4 t butylbenzotriazole azoles or naphthotnazoles are effective corrosion inhibt- 5 isobutylbenzotriazole tors for aqueous media, especially aerated aqueous media smetmlbenwtriazole and aerated solutions containing commercial detergents. @etmlbenzotriazole The compounds of this invention are represented by the iamYlb'enzotriaZole fflrmulae: 4-methyl-5-ethylbenzotriazole PENETRATION TYPE 4-methoxybenzotriazole 4-ethoxybenzotriazole N N l\ S-propoxybenzotrrazole N M N Rn fi-butoxybenzotrlazole H 7-methoxy-8-ethoxybenzotriazole 6-methyl-7-chlorobenzotriazole 5-butoxy--fluorobenzotriazole and 4-heptyl-5-propoxybenzotriazole N 4-pentoxy-6-iodobenzotriazole I 4,5-dichlorobenzotriazole M. N 4,6-dibromobenzotriazole 4,7-difiuorobenzotriazole 4-phenylbenzotriazole and I I 4-methy1naphthotriazole 4-methyl-5-ethylnaphthotriazole 4-n-propylnaphthotriazole 4,5-dibutylnaphthotriazole 4-methyl-8-phenylnaphthotriazole 6-nitro-7-p-methylphenylnaphthotriazole 4-chloro-naphthotriazole fi-fiuoro-naphthotriazole 7,8-dibromonaphthotriazole 4-cyclobutylnaphthotriazoie S-cyclopentylnaphthotriazole Aziminophenazine 4-methylaziminophenazine 4-methyl-l l-methylaziminophenazine 4decylaziminophenazine fi-ethylaziminophenazine 6,7-dipropylaziminophenazine 4,6-dinitroaziminophenazine 9,11-dioctylaziminophenazine 4,6-dichloroaziminophenazine 4,6,9,1 l-tetralluoroaziminophenazine It is to be understood this this invention encompasses as specific non-limiting examples of corrosion inhibitors any polyvalent metal complex or any metal salt complex of the foregoing benzotriazoles, naphthotriazoles and aziminophenazines.

The benzotriazoles used in preparing the corrosion inhibitors of this invention are prepared by the action of nitrous acid on o-phenylene diamine to form azimidobenzene or aziminobenzene, also called benzo-l,2,3-triazole, a well-crystallized, odorless compound, melting at about 100 C. Aziminotoluene, thusly prepared, melts at 83- 84 C. These compounds are stable towards acids and alkalies and resist oxidation and/or reduction. They form stable metallic salts.

2,3-diaminophenazine is prepared by the oxidation of o-phenylene diamine with ferric chloride in acetic acid solution, from which the triazoles, such as aziminophenazine is prepared through the action of nitrous acid by the reaction N O N O j U /N N NHQ v Aziminophenazine also forms innermetallic complexes, e.g., with copper and nickel, to be used in accordance with this invention.

The metal salts that may be used include, by way of illustration, copper sulfate, cobalt sulfate, nickel sulfate, copper chloride, cobalt chloride, nickel chloride, copper bromide, cobalt bromide, copper nitrate, and cobalt nitrate.

The reaction of the benzotriazoles or naphthotriazoles with the foregoing metal salts is readily carried out using known techniques, and the initial formation of the associated complex is observed by the formation of a precipitate. The associated complex with the anion of the metal salt may be used as such, or transformed by heat or alkali to the penetration complex form. The alkali added to promote the formation of the penetration complex form may be ammonium hydroxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium oxide, barium hydroxide, and similar alkalies.

The reaction is carried out at a temperature of about 20 to 100 F., under atmospheric conditions, using equimolar quantities of the benzotriazole or naphthotriazole and metal salt. Preferably, an excess of the metal salt is used and the alkali is added to the reaction mixture slowly with constant stirring.

In order to demonstrate the invention, the following non-limiting examples are given:

The effectiveness of our inhibitors has been demonstrated by a series of experiments with aqueous solutions of Tide, a commercial detergent composition containing alkylaryl sulfonates, sodium tripolyphosphate, sodium sulfate, and other components. First, a water solution of Tide" (5.0 g./liter) was prepared. A 50-ml. portion of this detergent solution was charged to each of three flasks. Two polished brass strips /2" x 3") were placed in each of the flasks, and our inhibitors were placed in the indicated concentration in two of the flasks. Air, at a rate of 20-30 ml./min., was bubbled through the solutions for a period of 72 hours while the temperature was held constant at 70 C. The weight losses per strip were as follows:

Table I Cone. of Wt. loss Corrosion Inhibitor inhibitor (percent) expressed (percent w.) (avg. 01 as inch two strips) per year None 0. 0 2. 21 0. 0865 Copper bls-benzotriazole. 0. l 0. l1 0. 0035 Nickel bisbenzotriazole. 0. 025 0. 008 0. 0003 As is known, the corrosion rate in inches per year is the significant measure of the inhibiting effect, same being calculated from the weight and size of the strip, its weight loss in grams, the time factor and the density of the metal.

This invention is directed to inhibiting corrosion in aqueous environments in contact with metal surfaces. It has been demonstrated in relation to aqueous solutions of commercial detergents containing builders such as polyphosphates and alkali metal sulfates. The following experiments demonstrate that the presence of these builders, particularly the phosphates, causes the corrosion and that the surfactant agent, i.e., dodecylbenzene sodium sulfonate, itself does not contribute to the corrosion.

In these experiments, pure synthetic dodecylbenzene sodium sulfonate and reagent grade sulfate, phosphate, metasilicate, pyrophosphate and tripolyphosphate salts were used and the procedure in the foregoing experiments was followed:

Table II Blend Wt.per- Corrosion, Corrosion, No. Component cent wt. perinch/year cent loss 11530 gain. 0.25

g n-. D so 0.11 Sodium sulfate 20 0.04 0.0009 Trlsodium phosphate-.. 4 DBSS Sodium suliate 0. 07 0. 0017 B88 goginm sulfattilunfiflfu 1. 04 0. 041

o um re 05 a e. 0 DBSS Dy p 'DBSSabbrcvietion for dodecylbenzcne sodium sullonate.

Within this environment, i.e., blend #5, the presence of about 0.2 g. of copper, nickel, or cobalt bis-benzetriazole or mixtures thereof will reduce the corrosion loss to about 0.10 to 0.20 percent wt., equivalent to about 0.006 to 0.012 inch per year. These results are significant since the concentration of pyrophosphate or polyphosphate in the blends tested in Table II are above the concentrations of these builders in commercial detergent compositions, which are about 5 to 20% by weight.

The compounds of this invention are colored solids. The cobalt and nickel complexes are violet, and the copper complexes are red. They are water insoluble and have limited solubility in organic solvents. However, the complexes aresufiiciently soluble or dispersible in aqueous media to provide corrosion protection since only about 0.0001 to 0.2 g. per 100 ml. of solution is necessary for this purpose. The presence of detergents, alkalis other salts, organic solvents, etc.,'in the aqueous media or emulsion aids in solubilizing the compounds of this invention are soluble to the extent necessary to inhibit corrosion in aqueous detergent compositions having a pH of about 8 to 11.

The compounds of this invention act as corrosion inhibitors for a variety of metals and alloys, e.g., iron, steel,

aluminum, brass, copper, and the like which are subject to a corrosive atmosphere in liquid or vapor form. Generaliy, the presence of air or oxygen in aqueous media greatly increases the rate of corrosion in such environments, particularly if a detergent or surfactant is present. The art recognizes that organic compounds such as amines, mercaptans, hete ocyclic nitrogen compounds, substituted ureas and thioureas, ctc., containing nitrogen, oxygen, sulfur, and other members of Groups V and Vi of the Periodic Table, can be used to inhibit such corrosion. Howcver, the effectiveness of these compounds, the concentrations necessary, and cost and other factors,

militate against the use of many of these inhibitors on a commercial basis.

Many commercial detergents contain builders, such as polyphosphates and pyrophosphates, to assist the washing action and prevent the formation of insolubles. Normally, in the use of detergent compositions in machinery such as found in launderies or factories, the coatings of corrosion products and other insolubles form a protective layer on the metal surfaces. The presence of builders or the use of highly etlective detergents prevents or removes this coating and promotes corrosion of the metal surfaces.

The innermetallic or associated complex of benzotriazoles of this invention are elfective as corrosion inhibitors in aqueous solutions, aerated aqueous solutions, detergent solutions, and aerated detergent solutions to overcome this and related corrosion problems. The detergent compositions with which the corrosion inhibitors of this invention can be used contain any type of detergent, soap, builder or combination of these ingredients.

Although the invention has been illustrated by the use of a mixed aryl alkyl snlfonate detergent composition, it is not to be limited thereto. The corrosion inhibitors of this invention can be used in mctal-cleaning compositions, steam cleaners. skin detergents, car-washing compositions, metal-pickling solutions, lubricating oil compositions, cutting oils, grease emulsifiers, low-sudsing allpurpose emulsifier. compositions or detergents for household use, dispersant or emulsion paints, latex paints, waterbase inks, glues, galvanizing fluxes, electrolyte solutions, agricultural emulsifier formulations, anionic textilesofteners, dye baths, warp-sizing compositions, textilcand leather-treating compositions, dishwashing compositions, etc., that is, any of the known detergentor surfactantcontaining compositions. Examples of various surfactants that may be contained in or be present in the aqueous environment to be inhibited by the compounds of this invention are the anionic and cationic surfactants such as dodecylbenzene sulfonic acid, salts of fatty acid tertiary amines, alkyl aryl sulfonate, sulfonated oils, alkyl aryl polyether alcohols, polyglycol esters, disodium N-octadecylsulfosuccinimate, ethanolated alkyl guanidine amine complexes, dihexyl ester of sodium sulfosuccinic acid, fatty carbamide derivatives, petroleum sulfonates, sulfated fatty alcohols, blends of alkalies and detergents, blends of non-ionic and cationic agents, jcetyl dimethyl benzyl ammonium chloride, alkyl polyoxyethylene glycol amide, sorbitan monolnurate, sorbitan sesquioleate, and others.

The foregoing synthetic detergents, emulsifiers and surfactants along with ordinary soaps and alkalis including phosphates, carbonates, sulfates, acetates and mixtures of same, wherein the cation may bean alkali metal or an alkaline earth metal, are used in aqueous solutions in. amounts ranging from about 0.1 g. to 10 g./100 ml. of

solution, or about 0.001 to 0.2% by weight, having a pH of about 8 to 11, to make up a wide variety of cleaning, scouring, detergent and emulsifier compositions to which the corrosion inhibitors of this invention can be applied or incorporated. The invention also relates to the method of inhibiting the corrosion of metal parts in contact with detergent compositions by incorporating therein a corrosion-inhibiting amount of the compounds of this invention.

In defining the complexes of this invention, particularly the penetration type, it must be kept in mind that the metal, that is, copper, nickel, or cobalt is no longer associated with various anions, such as phosphate, chloride, bromide, iodide, nitrite, sulfate, and nitrate, coming from the metal salt used in its preparation or subse-# quently added and incorporated through the alkalis that are generally used in detergent compositions as blenders, ibuilders, etc.

Specific exam-pies of other innermetaliic complexes that can he prepared by following the examples given herein are:

Copper bis-2-methylbenzotriazole Nickel bis-Z-n-propylbenzotriazole Cobalt bis-7-decylbenzotriazole Copper bis-4-chlorobenzotriazole Nickel bis-4,6-diiodobcnzotriazole Cobalt bis-2-phenylbenzotriazole Nickel bisQ-nitrobenzotriazole Nickel bis-Z-methoxybenzotriazole Copper bis-4-pentoxybenzotriazole Specific examples of compounds of the associated type include:

Copper benzotriazole sulfate Copper benzotriazole chloride Copper benzotriazole acetate Copper benzotriazole phosphate Nickel benzotriazole sulfate Nickel benzotriazole chloride Cobalt benzotriazole phosphate Nickel 2-ethylbenzotriazole sulfate Cobalt Z-n-butylbenzotriazole chloride Cobalt 4 bromobenzotriazole bromine Nickel 2-ethoxy-4-methoxybenzotriazole phosphate Non-limiting examples of specific R and R groups coming within the definition of this invention are hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, hexyl, heptyl, octyl, nonyl, decyl; the corresponding alkoxy groups such as methoxy, ethoxy, bu-

toxy, propoxy, heptoxy, etc., phenyl, naphthyl, anthryl, I

tions attaching thereto are found in the appended claims.

The embodiments of this invention in which an exclufive property or privilege is claimed are defined as folows:

1. A composition of matter consisting essentially of an organic surfactant, salts from the group consisting of sodium pyrophosphate and sodium tripolyphosphate, in amount sufiicient to cause corrosion of a metal surface when said composition in aqueous medium is contacted with said metal, and an amount sufiicient to inhibit corrosion of said metal of inner complexes having the formula wherein M is from the group consisting of polyvalent metals and salts of metals of the group consisting of cobalt, nickel and copper and A is the same divalent substituent of the group consisting of wherein R is a member of the group consisting of halogens, alkyl radicals of l to 10 carbon atoms, aryl radicals of 6 to 18 carbon atoms, alkaryl radicals of 6 to 18 carbon atoms in the aryl portion and 1 to 10 carbon atoms in the alkyl portion, aralkyl radicals of 1 to 10 carbon atoms in the alkyl portion and 6 to 18 carbon atoms in the aryl portion and alkoxy radicals having 1 to 10 carbon atoms, and n has a value of to 4.

2. The composition in accordance with claim 1 in which M is a salt of an union of the group consisting of phosphate. chloride, bromide, iodide, sulfate and nitrate.

3. A composition in accordance with claim 1 in which said surfactant is mixed aryl alkyl sulfonates.

4. A composition in accordance with claim 1 which contains about 520% by weight of said salts.

5. The composition in accordance with claim 1 in which the inner complex is present in sufficient amount to provide a concentration of' about 00001 to 0.2 gram when the composition is mixed with the aqueous medium.

6. The composition in accordance with claim 5 in which A is and n is zero.

7. The composition in accordance with claim 5 in which A is and n is zero.

8. The composition in accordance with claim 5 in which A is and n is zero.

9. The method of inhibiting corrosion of metal surfaces exposed to aqueous surfactant-containing compositions having a pH of about 8 to "11 comprising contacting such surfaces with such compositions in the presence of not less than about 0.0001 gram/100 ml. of aqueous composition but sufficient to inhibit corrosion of said surfaces, of innermetallic complexes having the formula wherein M is from the group consisting of polyvalent metals and salt of metals of the group consisting of co- -ba1t, nickel and copper and A is the same divalent substituent of the group consisting of o: on

wherein R is a member of the group consisting of halogens, alkyl radicals of 1 to 10 carbon atoms, aryl radicals of 6 to 18 carbon atoms, alkaryl radicals of 6 to 18 carbon atoms in the aryl portion and 1 to 10 carbon atoms in the alkyl portion, aralkyl radicals of 1 to 10 carbon atoms in the alkyl portion and 6 to 18 carbon atoms in the aryl portion and alkoxy radicals having 1 to 10 carbon atoms, and n has a value of 0 to 4.

10. The method in accordance with clam 9 in which the aqueous medium contains compounds from the group consisting of sodium pyrophosphate and sodium tripolyphosphate in sufiicient amount to cause corrosion of the metal.

11. The method in accordance with claim 10 in which the innermetallic complexes are present in an amount of about 0.0001 to 0.2 gram/ ml. of aqueous medium.

'12. The method in accordance with claim 11 in which A is and 13. The method in accordance with claim 11 in which A is 14. The method in accordance with claim 11 in which A is his References Cited by the Examiner UNITED STATES PATENTS 2,406,692 8/1946 Jones et al 252390 XR 2,618,606 11/1952 Schaefier et a]. 252137 2,618,608 11/1952 Schaeffer et a1. 252--390 XR 2,784,183 3/1957 Keller et a1. 260308 XR 2,868,798 1/1959 Kehr 260299 2,870,092 1/1959 Ruff 252137 2,870,093 1/1959 Ruff 252137 2,881,176 4/1959 l-logsett 260-299 2,941,953 6/1960 Hatch 252390 XR 3,054,800 9/1962 Burchfield ct al. 260-299 JULIUS GREENWALD, Primary Examiner. 

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF AN ORGANIC SURFACENT, SALTS FROM THE GROUP CONSISTING OF SODIUM PYROPHOSPHATE AND SODIUM TRIPOLYPHOSPHATE, IN AMOUNT SUFFICIENT TO CAUSE CORROSION OF A METAL SURFACE WHEN SAID COMPOSITION IN AQUEOUS MEDIUM IS CONTACTED WITH SAID METAL OF INNER COMPLEXES HAVING THE FORMULA SION OF SAID METAL OF INNER COMPLEXES HAVING THE FORMULA 